1. Field of the Invention
The present invention relates to a semiconductor device with parts mounted on a surface of a substrate and with a cap for radiating heat provided over the parts.
2. Description of the Background Art
Conventionally, semiconductor modules with parts mounted on surfaces of respective multi-layer substrates have been known. For this kind of semiconductor modules, a requirement exists that parts are mounted in an efficient mounting area. Therefore, some of semiconductor modules have cavities provided on rear surfaces of respective multi-layer substrates so that semiconductor chips can be arranged in the cavities. This kind of semiconductor module has a heat sink located on another surface of the multi-layer substrate opposite to the surface where the semiconductor chip is provided. The heat sink is joined to the cap of semiconductor module. Because the cap is formed by metal with high thermal conductivity, heat liberated from the semiconductor chip is radiated via the heat sink and the cap. According to this arrangement, the semiconductor module stably operates.
In recent years, requests for downsizing products such as cellular phones have increased, and as a result, a need to still further downsizing semiconductor modules such as power amplifier modules arises.
In the arrangement of the conventional semiconductor module, the module cannot be downsized because the size of heat sink is respectively large. The reason is that a fear of short-circuiting the cap and chip parts arises, when the heat sink and the cap are downsized to suppress size of the module.
For example, consider the case to change the heat sink from type 1608 (1.6 mmxc3x970.8 mm) to type 1005 (1.0 mmxc3x970.5 mm) that bulk feeders can operate. Level of the heat sink reaches the same as that of other 1005 chip parts (for example, L, C, R). Depending on tolerances of chip parts, the cap and chip parts may electrically short-circuiting. Note that the term xe2x80x9ctolerancesxe2x80x9d means a difference in size between maximum and minimum values allowed from the viewpoint of specifications.
Although it is possible to change all the chip parts to type 0603 (0.6 mmxc3x970.3 mm), some of the parts of type 0603 do not satisfy necessary characteristics. Thus, cost increases as a result. In addition, in the case caps are not used and heat is radiated through, for example, molds, shielding capability for preventing leakage of electric power as well as influence on peripheral parts is required for current products. To provide shielding capability, further different configuration is required, and as a result, downsizing is unable to be achieved and the cost increases.
It is an object of the present invention to provide a semiconductor device of an arrangement in which chip parts and caps are not short-circuited and at the same time which achieves downsizing.
The first semiconductor device according to the present invention includes a substrate, a semiconductor chip, at least one chip part, a heat sink, a cap and an insulator. The substrate has a first surface with a cavity and a second surface on the opposite side of the first surface. The semiconductor chip is arranged in the cavity and electrically connected to the substrate. The at least one chip part is mounted on the second surface of the substrate and electrically connected to the substrate. The heat sink is mounted on the second surface of the substrate and transfers heat liberated from the semiconductor chip. The cap is fitted to the substrate, covers the second surface of the substrate, and is joined to the heat sink. The insulator is provided between the cap and the at least one chip part.
By providing the insulator, for example, thermoplastic resin, short-circuiting of the chip part and the cap is prevented. Consequently, a distance between the cap and chip part can be shortened to downsize the size of semiconductor device. The size of the semiconductor device can be further and more effectively downsized by reducing size of the heat sink.
The second semiconductor device according to the present invention includes a substrate, a semiconductor chip, at least one chip part, a heat sink and a cap. The substrate has a first surface with a cavity and a second surface on the opposite side of the first surface. The semiconductor chip is arranged in the cavity and electrically connected to the substrate. The at least one chip part mounted on the second surface of the substrate and electrically connected to the substrate. The heat sink is mounted on the second surface of the substrate and transfers heat liberated from the semiconductor chip. The cap is fitted to the substrate, covers the second surface of the substrate, and is joined to the heat sink. Further, the cap is bent in the substrate direction at an outer edge of a region where the cap is joined to the heat sink. According to the above arrangement, short-circuiting between the cap and chip parts can be avoided without providing insulation film between the cap and chip parts.